Catalytic isomerization of propylene oxide to propionaldehyde, catalyst therefor, and synthesis of catalyst



Patented June 24, 1952 CATALYTIC ISOMERIZATION F PROPYL- ENE OXIDE TO PROPIONALDEHYDE, CAT- ALYST THEREFOR, AND SYNTHESIS OF CATALYST Lester G. Lundsted, Grosse Ile, Mich., assignor to Wyandotte Chemicals Corporation, Wyandotte, Mich., a. corporation of Michigan No Drawing. Application July 2, 1948,

. Serial No. 36,807

Claims.

The present invention relates to the catalytic isomerization or molecular rearrangement of propylene oxide (preferably Lil-propylene oxide) to produce, as themajor and predominant product, propionaldehyde. The invention also relates to a novel catalyst composition for such. isomerization process, as well as the method of synthesizing such catalyst.

The isomerization of alkylene alpha oxides to aldehydes has constituted a field of study and experimentation by organic chemists for more than the past 40 years. Ipatiefi and Leontovitch (Berichte vol. 36, p. 2016, 1903) first discovered that such isomerization of olefin oxides could be effected by the use of alumina as the catalyst. Then, beginning in71930 Baur (U. S. Patents 1,906,833 and 2,031,200), Young et a1. (U. S.

Patent 1,917,179) and Law and McNamee (U. S.

Patent 2,159,507) extended the work to include other catalysts. magnesium pyrophosphate and cerous sulfate from which propionaldehyde was obtained in good yield (see Examples 1 and 2 of U. S. 2,031,200) and barium bromide and magnesium oxychloride, from .which the propylene oxide conversion product contained a maximum yield of 60% propionaldehyde (see Examples 1 and 2 of U. S. 1,906,833). Law et a1. disclosed the use of alum" type catalysts, such as potassium aluminum sulfate, ammonium aluminum sulfate, potassium chromate and potassium ferric sulfate (U. S. 2,159,507). According to Law et al. (p. 1, col. 1, ll. et seq.) oxy acids, anhydrides and salts of the elements of the fifth and sixth groups of the periodic table, were subject to the disadvantage as catalysts in the isomerization of propylene oxide, in that the condensation or polymerization of propionaldehyde was promoted rather than being retarded.

I have now discovered that the catalytic isomerization of propylene oxide to propionaldehyde can be conducted in the presence of a chromicoxide-tungstic oxide catalyst composition. Such catalyst'composition is a complex, the exact identity of which is not yet established, but conforming to the formula XCI2O3.WO3 and for results wherein a high conversion of propylene oxide and a high percentage of propionaldehyde in the conversion products are desired to be obtained, X has a value of more than 4 and less than 75. I have discovered that as high as a 100% conversion of the propylene oxide, and up to 88% of propionaldehyde in the conversion products (herein called yield") can be obtained bythe catalytic isom'rization process employing Baur disclosed such catalysts as such chromic oxide-tungstic oxide catalyst. This unusually high conversion and high yield of propionaldehyde exceeds the best (cf. overall yields" and efilciencies, of examples of U. S. 2,159,507, equivalent to conversions and yields," respectively, of the instant application) that have heretofore been obtainable.

The catalytic isomerization process of my invention is also of an unexpected nature when it is considered that a chromic oxide gel catalyst alone promotes isomerization of propylene oxide principally to allyl alcohol; propionaldehyde being a minor product. See co-pending U. S. patent application Serial No. 588,710, filed April 16, 1945, now Patent Number 2,479,632 by Lester G. Lundsted, Edward J. Schwoegler and Edward C. Jacobs, said Lundsted being applicant herein.

My invention also possesses the additional advantage in that the chromic oxide-tungstic oxide catalyst possesses an unusually high catalyst life, or period of catalytic activity. In other words, such catalyst not only remains active for a relatively long period of time before requiring regeneration, but possesses a renewed and high degree of catalytic activity after regeneration, so that the original catalyst mass can be repeatedly used and re-used in the process without the necessity of being discarded.

PREPARATION OF CATALYST Example 1 0 Four hundred grams of chromium trioxide and grams of tungstic acid were ground in a ball mill for two hours until the mass appeared homogeneous. The resulting powder was transferred to a porcelain evaporating dish and heated in an oven at 200 to 220 for 24 hours to decompose a portion of the chromium trioxide. At the end of this period the dish containing the mixture was transferred to a mufile furnace and heated to l000 during a period of four hours. Violet fumes, probably a result of the decomposition of the chromium-trioxide, were liberated during this period. The mixture was held at 10 00" for four hours and then allowed to cool in the furnace to give a bright green porous cake weighing 357.7 grams. This cake was broken up and used directly for catalytic studies. Analysis of the product showed 77.5% CI'2O3 and 21.3% W03 corresponding to a mol ratio of 5.5 to 1.

Example 2 In this method of preparation of the chromic oxide-tungstic oxide catalyst. a nreninitntn time "(Cr(N03')3-9HzO)-in 250 m1. of distilled water were added 234 grams of sodium tungstate dihydrate (Na2WO4-2H2O). The pale green precipitate which formed was filtered off and dried in an oven at 110 to yield a bright green cake covered by large needles of sodium nitrate. The

mol ratios were as stated in the following table.

The percentages of conversion and "yield as employed in this table have the following definitions:

Percent conversion= Per'acent yie1d= solid was crushed and washed with distilled water until tests for nitrate ion withferric sulfate-sulwt. of product X 100 furic acid and for sodium With magnesium uranyl wt, (j'f'propylene oxide consumed Table I I v PYield of1 Y'Max. Conropmm a .Gontrol 1 Linear Space Time on dehyde g 5 35, 6 Temp. 3 Velocity Velocity Stream (Percent of 2 8 3 C. .1 ft./sec. g./1/hr. hrs. 5f Converted Propylene Oxide) panels-2 0. /1 250 3 00 l -024" 335; 38.4 s9. 0 *0 191613-1' 0. 28/1 250 286 025 520 24L 6 69. 5 .o-1ss5' 10.82/1 250 265 I 1 384;; :24 j as. 2 4.2/1 300. 331. -039 300;. '13 7&0 {1.7/1 215 270 .034 198 "337.3 35. 7 5;,6/1 215 .1 300 032 1285 5.9 -88. 3 1 1..fl/1 215 315 036 320, I5 84. 2 23. 0/1 215: 312 037' 328" 6 85. D :35. 7/1 215 270 Q O34 6 81. 3 7 3. 0/1 215 272 .034 305 5 186i 0 138/1 215 314 037 327 935 '72. 4

" Catalystmade by method of Example 2, all others bymethod'of-Exam'ple' l.

acetate were negative. The solid material was removed by filtration and dried at 120 to 150 in an oven. The'finished product, weighing 221.3 grams analyzed75l2% tungsten as tungsten trioxide and 14.8% chromium as chromic oxide. Loss on heating at 180 was 5.11%. "This corresponded to a molratio of 0.33 mol CrzOa per mol of W03.

PROPYLENE OXIDE .ISOMERIZATION Several 'chromic oxide-tungstic' oxide catalyst compositions, made according "to the'foregoing examples, but'in which the Cr2O3WOa'ratio was varied, "were then placed ini'a 'glassltubular heating furnace measuring mm; by 600mm,, wound with electrical resistance heating wire as the heat source and packed with'gla'ss wool in the top and bottom of the glassheating furnace. A thermocouple was located in the glass wool section in the top of the tube, which section functionedas the preheater for the propylene oxide fed down through the top of the glass tube furnace. A second thermocouple'was' located within the interior of the cat'a'lystbed. The'temperature of the furnace was automaticallycontrolled. The rate of flow of the propylene oxide through the furnace was measuredboth in terms of linear feet per second and grams per hour per liter of catalyst. The determinationof theflow velocity in terms of linear velocity or "feet per second, instead of space velocity or grams 'per hour per liter of catalyst, is preferred in the present process because it has been found by experience to be'a morereliable and more readily re-producible method of measurement.

The products were analyzed by an infrared spectograph, this proving to be the most reliable method for correctly determining propionaldehyde in the presence of acetone and other possible "products such as allyl alcohol and 'dimethyl dioxane.

The results obtained on the several catalyst compositions so tested as having varying 'ing an The results of the foregoing tablethusconfirm the previous statement that the preferred range of CI'2O3/WO3 moliratio in the 'catalyst'compo- 'sition is greater thangi to1 and less'than '75'to' 1. Beyond the upper and lower limits 'of'this range, it will be seen that there isa materialidepreciation in either the conversion percentage, or? the proportion of propionaldehydeini'the "converted products. 'In this optimum'crzoalwoamol ratio range, the percentage conversion is "practically (i. e. 97.'2-100'.'%) and "the percentage of propion'aldehycle in the converted pr'oduc'ts is BOD-88.3%.

Preferred operating conditions were established as in the ranges of 0.02-0.07 feet per second .linear velocity of .propyleneoxide and a furnace control temperature of 200-300 C.

CATALYST!v LIFE. TESTS "Two catalyst compositions, prepared according to Example lianjd havin "the CrzOa/WOrmol ratios of 35.5/1 and 4.771 respectively. "were placed in a stainless steelhea'tingfurnace havinterior cataly'stec'ontaining chamber measuring 1" by 43. heating chamber was enclosed in a "fluid-type jacket containing Dowth-erm fluid. The heat "source wa'stprovided by two parallel electric heatin'g'Jelements wound around the ou er. jacket and having a capacity of 15 amperes at '110 volts. Suitable thermocouples and thermostatically controlled rheostats were provided .for maintaining and measuring furnace temperature and the catalyst bed temperature. The catalyst wasfplaced in the interior of the stainless steel. heating furnace tulbe, forminga catalyst. bed of 12" depth.

Each one of the 35.5/1 and. 4:771 .'C1203/WO3 mol ratio catalyst compositions was subjected to operating cycles totalling 652.5 and. 5632. hours of operation respectively. vAt the end or each operating cycle (the minimum cycle beingi109.8 hours), the catalystwas regenerated by heating in an air stream until" analysis of exhaust gases showed the same percentages of oxygenasthe feed' gases. This was talren'as an indication .that

carbon and resinous deposits-had been burned off and the catalyst was ready for re-use.

The results taken from the second and fourth cycles of such catalyst life study tests are tabulated as follows:

6 4. The process of claim 1 wherein the propylene oxide vapors are passed over the catalyst at a linear velocity of 0.02-0.07 feet per second.

5. The process of making propionaldehyde comprising passing propylene oxide vapor over Catalyst No. -2183 Catalyst No. 0-2209 (35.5 1 (moi/W08) (4.7/1 CrzOa/WOz) Cycle Number Average space velocity, g'./1/hr 212 191 198 207 Average linear velocity, it/sec 0.0365 0.033 0. 034 0. 038 Propylene oxide feed, g 3, 602 3, 106. 5 4,499 2, 504 Products recovered, g 3, 527 3, 022 4, 393 2, 454 Total conversion to g.:

Propionaldehyde a, 002 2, 482 a, 746 2, 082 58.7 64.0 38.2 311.6 292. a 274 179.8 112. 5 191.1 190 14a. 2 99.4 100 97.5 99.5

83.8 80.3 85.7 81.2 2.1 1.2 1.4 1.6 3.7 9.2 6.2 7.3 3.3 as 4.2 6.0 ss 2.1 2. 8 2. 5 3. 9 Average production/24 hrs. g./l

catalyst: Propionaldehyde 4, 180 3, 140 3, 960 4, 181 Acetone 81. 2 67. 7 77 Allyl Alcohol 430 404 290 962 Unidentified (principally dimethyl dioxane) 156 266 201 294 From the foregoing table, it Will be seen that a heated chromic oxide-tungstic oxide complex even at the end of the fourth cycle or run in catalyst, said catalyst being selected from the each case, that the conversion percentage regroup consisting of a catalyst prepared by I'vmained at it m imu and th yie1d of proacting chromium nitrate with sodium tungstate pionaldehyde was 'still over 80 111 q ffi l Solution, Washing the precipitate free other mgdes of applying the principle of my 01' SOdlllln nitrate and filtering and heat-drying invention may be employed, changes being made t precipitate, and a Catalyst p p d y heatas regards to the details described, provided the 111ar an intimate p ysical mixture of chromic oxfeatures stated in any of the following claims or i018 and tu gst a 130 f a 001111119X eof the equivalent of such be employed. having high catalytic activity, said catalyst hav- I, therefore, particularly point out and dise h fOllr and less than 75 mols CI'203 tinctly claim as my invention: 40 per mol of W03, at a temperature of at least 200 1, The process of making propionaldehyde C. and at a linear velocity of 0.02-0.07 feet per comprising passing propylene oxide vapor over a Secondheated chromic oxide-tungstic oxide complex LESTER G. LUNDSTED. catalyst selected from the group consisting of a catalyst prepared (by reacting chromium nitrate ENCES CITED With Sodium t st in queous solution, WaSh- The following references are of record in the ing the precipitate free of sodium nitrate and file of t patent; filtering and heat-drying the precipitate, and a catalyst prepared by heating an intimate physi- UNITED STATES PATENTS cal mixture of chromic oxide and tungstic acid to Number Name Date form a complex thereof having high catalytic ,031,200 Baur Feb. 18, 1936 activity. 2,159,507 Law et a1. May 23, 1939 2. The process of'claim 1 wherein the catalyst 2,338,089 Bond Jan. 4, 1944 contains more than four and less than 75 mols of 2,351,094 Blake! June 13, 1944 CrzOa per mol of W02. 2,439,330 old Apr. 20, 1948 3. The process of claim 1 wherein the propylene oxide vapors are heated to a temperature of at least 200 C. 

1. THE PROCESS OF MAKING PROPIONALDEHYDE COMPRISING PASSING PROPYLENE OXIDE VAPOR OVER A HEATED CHROMIC OXIDE -TUNGSTIC OXIDE COMPLEX CATALYST SELECTED FROM THE GROUP CONSISTING OF A CATALYST PREPARED BY REACTING CHROMIUM NITRATE WITH SODIUM TUNGSTATE IN AQUEOUS SOLUTION, WASHING THE PRECIPITATE FREE OF SODIUM NITRATE AND FILTERING AND HEAT-DRYING THE PRECIPITATE, AND A CATALYST PREPARED BY HEATING AN INTIMATE PHYSICAL MIXTURE OF CHROMIC OXIDE AND TUNGSTIC ACID TO FORM A COMPLEX THEREOF HAVING HIGH CATALYTIC ACTIVITY. 